The invention relates to an electroacoustic underwater antenna, in particular side antennas which can be fitted to the outer skin of underwater vehicles, of the generic type defined in the precharacterizing clause of claim 1.
A known side antenna for submarines (EP 0 214 525 B1) is formed by a so-called hydrophone streamer which is held over its longitudinal extent at a distance from the submarine casing, by holding elements which are attached to the submarine casing at a distance from one another. The hydrophone streamer has a flexible tube which is supported by moldings at specific intervals. The hydrophones, which are arranged at defined distances in the flexible tube, are each arranged between two moldings, which are supported on the casing of the flexible tube. The cylindrical hydrophones are in this case seated in a holder which is firmly clamped to tension cables. This holder is assembled from two resiliently flexible plastic halves, whose end sections, which each surround half of the tension cables, are held together by spring clips. The central part of the holder surrounds a cylindrical cavity, in which the hydrophone is held in a sprung manner. The flexible tube casing is filled with a liquid, preferably oil, which ensures good acoustic transmission characteristics between the hydrophones and the flexible tube casing.
A known underwater antenna (DE 198 12 356 C1) in the form of a so-called towed antenna has a flexible tube which is filled with a filler, in which a large number of hydrophones are arranged in a row one behind the other at a distance and are held approximately centrally in the flexible tube by being supported on the flexible tube casing. Moldings which are at a distance from one another in the longitudinal direction of the flexible tube and are composed of metal foam are provided in order to support the hydrophones, and the hydrophones are inserted centrally into them. The moldings are fixed to a tension cable, which passes through the flexible tube. The flexible tube is filled with oil.
In a likewise known underwater towed antenna (DE 195 18 461 C1), a gel is chosen as the filler which uniformly surrounds the hydrophones on all sides and thus fixes them essentially centrally in the flexible tube. The filler is a two-component silicone rubber, whose two components are in the form of thin liquids which can flow well, and which cure at room temperature to form a gel-like vulcanizate.
In one known underwater antenna (EP 0 654 953 B1), which is referred to as a so-called cylinder base, a large number (for example ninety six) of transducer arrangements in the form of rods, so-called staves, are mounted alongside one another on the outer casing of a hollow cylinder composed of glass-fiber-reinforced plastic. Each stave has a plurality (for example three) of hydrophones which are arranged at the same distance one above the other and are in the form of small spherical ceramics. A reflector is arranged behind the hydrophones in the sound incidence direction. The hydrophones and reflector are embedded in acoustically transparent hard encapsulation composed of polyurethane. The connecting lines for all of the hydrophones are passed to a common plug, which projects into a blind hole which is formed on one end face of the hard encapsulation. An underwater antenna such as this has a directional characteristic with a sufficiently narrow main lobe, in the vertical direction as well, on the basis of a plurality of hydrophones which are located vertically one above the other, with suitable signal processing of the hydrophone output signals.
The invention is based on the object of providing an underwater antenna of the type mentioned initially, which, in addition to a narrow main lobe of the reception characteristic which can be scanned in the horizontal direction, also has sufficiently good beam formation in the vertical direction and good reception sensitivity in the low-frequency range, and which furthermore can be produced easily from the production engineering point of view, and is simple to assemble.